JP2519498B2 - Electric powder molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to powder molding in which a die space is filled with powder as a molding material, and the powder is compression molded into a predetermined shape by a punch to obtain a machine part or the like. Regarding the machine.

Conventional technology In a powder molding machine equipped with a die (fixed mold) and punch (movable mold) in the molding section, the compressive force of the punch has a great influence on the state of powder compact (density and uniformity of density) in the molded product. ,
In the molding method in which a fixed amount of the raw material powder is supplied, the dimensions of the product are not uniform, and in the case of the molding method in which the raw material powder is supplied as needed until a predetermined dimension is reached, a product weight difference occurs.

However, in the conventional powder molding machine, the punch is driven by a simple hydraulic mechanism that simply repeats certain operations or a drive mechanism that is simply an electric motor. Due to the influence, it is difficult to always keep the set compression force constant and perform molding.

In addition, in order to be able to adjust the stroke and compression force of the punch, a complicated mechanism is required and the adjustment is complicated, and there is the aspect that it cannot respond immediately to changes in molding conditions such as changes in powder or shape.

In order to alleviate this situation as much as possible, there are cases where a large number of die setters that can adjust the die side according to each molding condition are prepared and replaced, but the die setter itself, a cam or an air cylinder assists. It has a complicated structure provided with driving means and is expensive. Also, it has been difficult to precisely control the compression force of the punch.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention provides a powder molding machine that enables the compression force of a punch to be controlled accurately and freely and that various adjustments can be easily made when the punch or die is replaced. And

Means for Solving the Problems In a powder molding machine, a molding unit is provided with a die and a punch, and a driving mechanism of the punch is a mechanism for driving the punch by a direct pressure of a ball screw, and this is connected to a servo motor and A control is provided in which a sensor for detecting the compression force of the punch is provided, and the compression drive of the servomotor at that time is controlled based on the compression force between the die and the punch until the output value of the sensor corresponds to the set compression force. Provide means.

The operation control means drives the servomotor based on the set value related to the compressive force of the punch and the detected value of the compressive force from the sensor,
The servomotor drives the punch through a mechanism that converts rotary motion into linear motion.

Embodiment In FIG. 1, a powder molding machine 1 has a frame 5 having an upper wall 2, a middle wall 3 and a lower wall 4, and from the top to the bottom along a vertical axis s penetrating these walls in a rigid direction. To the upper punch driving ball screw 6, upper punch 7,
Die 8, lower punch 9, lower punch driving ball screw
10 are arranged.

A ball nut 11 is rotatably mounted on the upper wall 2 and a servomotor 12 for driving the upper punch is attached to the upper wall 2. These are a gear 13 fixed to the ball nut 11 and an output shaft of the servomotor 12. A timing belt 15 is wound around the fixed gear 14 and is interlockingly connected.
The ball screw 6 for driving the upper punch is screwed into the ball nut 11 and fixed at the lower end so that the pressing force of the ball screw 6 directly acts (direct pressure) on the lower punch 7 and is replaceable. There is.

As in the case of the upper wall 2, the ball nut 16 is rotatably mounted on the lower wall 4 and the lower punch driving ball screw 10 is screwed onto the ball nut 16. A lower punch 9 is replaceably fixed to the upper end of the ball screw 10. The ball nut 16 is fixed to the gear 17, and is also interlocked with the gear 19 on the output shaft of the servo motor 18 for driving the lower punch, which is also attached to the lower wall 4, by the timing belt 20.

In the above, upper and lower punch driving ball screws
A pair of ball nuts 11 and 16 which are screwed together with 6 and 10 are mechanisms for converting rotational motion into linear motion, and are mechanisms for driving punches by servomotors 12 and 18.

A hole-shaped die mounting portion 21 is vertically penetrated through the middle wall 3, and the die 8 is mounted therein and fixed by a fixing member 22 so as to be replaceable.

The die 8 is also provided with a hole-shaped pressing die space 23 that penetrates vertically and is paired with the upper and lower punches 7 and 9. The upper and lower punches 7 and 9 are precisely fitted into the pressing die space 23 of the die 8 and can be vertically moved relative to the die 8.

Servo motors 12 and 18 for driving the upper and lower punches are both AC servo motors.
At 24, it is connected to a control device 26 via a servo amplifier 25.

The control device 26 has a normal configuration including an input unit, a storage unit, a comparison unit, an output unit, and a control unit that adjusts the operation of these units. In addition to the normal control for operating the punch, the following feedback control processing is performed. Done. That is, a detection value from the strain gauge 34 attached to the ball nut 11 and a set value regarding the compressive force of the punch from a key board or the like are input to the input section, and the storage section is provided with an operation program for various operations of the punch and The input set value is stored. Then, the comparison unit compares the detected value from the gauge 27 (after being converted into the compression force) with the stored set value at the timing of the control unit to determine whether the punch compression force has reached the set value. If it is determined that the set value has not been reached, the drive of the servo motor is continued, and if it is confirmed that the set value has been reached, the drive of the servo motor is stopped. That is, the compression drive of the servo motor at that time is controlled based on the compression force between the die and the punch.

The compression force of the punch can be detected by a load cell or the like in addition to the strain gauge 34 as described above, and the mounting position is not limited to the ball nut 11 but a position related to the drive mechanism of the upper punch 7 and the lower punch 9. Is possible.

The key board for inputting the set value, the sensor for detecting the compression force, the control device to which these are connected, the servo amplifier, and the like constitute the control means for the servo motors 12 and 18.

In FIG. 1, reference numeral 27 is a hopper for feeding raw material powder, which is connected to a lower feed shoe 29 by a flexible hose 28. The feed shoe 29 is a container having an open bottom, and the solenoid 30 pushes the upper surface of the middle wall 3 to form space 23.
It is moved to just above and pulled back. Further, reference numeral 31 is a device for pushing down a molded product, which is driven by a solenoid 32. A chute 33 for taking out the molded product to the outside is arranged on the opposite side of the lowering device 31 with the lower punch 9 interposed therebetween. The molding product dropping device 31 and the chute 33 may be provided on the upper surface side of the middle wall 3 or on both sides of the upper surface and the lower surface.

The molding operation is performed as follows according to the program selected by the control device 26 from the stored operation program after setting the upper punch 7, the lower punch 9 and the die 8 selected according to the molded product.

Initially, the upper punch 7 is pulled upward from the die 8 fixed to the middle wall 3 and moved to the retracted position, and
The lower punch 9 is fitted into the die space 23 of the die 8 to form the bottom of the die space 3. When this molding material acceptance state is confirmed, the solenoid 30 is activated and the feed shoe is
29 moves to the press die space 23 to fill the press die space 23 with the molding material, and is immediately returned to the original position. Then, the servo motor 12 for driving the upper punch is driven, the ball nut 11 is rotated through the gear 14, the timing belt 15, and the gear 13, and the ball screw 6 for driving the upper punch is lowered to move the upper punch 7 Is inserted into the die space 23 of the die 8. As a result, the molding material inside the pressing die space 23 is pressed between the upper punch 7 and the lower punch 9 which are directly pressed by the upper punch driving hole screw 6 and the lower punch driving ball screw 10, respectively.

In this case, various modes can be adopted for the operation of the lower punch 9 and the upper punch 7.

When the servo motor 18 for driving the lower punch is locked by an electromagnetic brake or the like, the lower punch 9 is stopped at a fixed position, and the molding material is molded only by the pressing force of the upper punch 7.
This is almost the same as the conventional molding, but the density of the powder in the molded product is uniform by feedback control based on the compression force of the punch, and the variation in weight between the molded products is extremely small.

When the servo motor 12 for driving the lower punch is driven together with the servo motor 12 for driving the upper punch, and the molding material is pressed from above and below for molding. Since a strong pressing force is exerted and pressing is performed from both sides, a portion where the density of the powder compact is relatively low in the molded product can be set at the center in the vertical direction.
Alternatively, if necessary, the pressing force between the upper punch 7 and the lower punch 9 is made different to control the pressing force, so that the portion where the density becomes low can be set at an arbitrary position in the vertical direction of the molded product. Also in this case, the density and the weight of the powder compact can be made equal among the products by using the feedback control regarding the compressive force of the punch together.

When alternately operating the upper punch 7 and the lower punch 9. A high density and uniform molded product can be obtained by a kind of vibration due to the alternate pressing and the movement of the internal density distribution, and the variation between products can be eliminated by controlling the compression force of the punch to be constant.

The case where the pressing by the upper punch 7 is performed each time the molding material is supplied a plurality of times. A compacted product having a uniform green compact density can be obtained even in an elongated molded product having a complicated shape due to the tamping effect. In this case, the upper punch 7 is gradually moved upward while repeating fine movement (vibration) in the vertical direction, and when the molding material is supplied during that time, the operation of leaving the pressing space 23 and returning to the retracted position is repeated. However, by performing feedback control of the compression force of the punch with respect to the set value, it is possible to obtain a product in which the compression force in each of the above repetitions is made constant and the density of the powder compact is highly uniform. On the other hand, it is possible to obtain a product in which the density of the green compact has a predetermined change.

When it is confirmed that the compressive force of the upper punch 7 and / or the lower punch 9 has reached the set value, the pressing force between both punches is slightly relaxed, and then both punches 7 and 9 move downward while holding the molded product. Alternatively, the molded article is moved upwards) to escape from the pressing die space 23 of the die 8. Then, the upper punch 7 moves to the retreat position while leaving the molded product left on the lower punch 9, and the molded product is moved from above the lower punch 9 by the thrusting device 31 operated by the solenoid 32 which is urged at this time. Shoot 33 is dropped. Then, the lower punch 9 is driven by the servo motor 18 for driving the lower punch to be inserted into the pressing die space 23 of the die 8 and stopped, and the lower punch 9 moves to the next molding cycle.

If all the driving of the powder molding machine is performed by the servo motor of the control device, there will be no oil stain and a comfortable working environment with less noise and vibration can be realized, and if the punch is driven directly by the servo motor, the efficiency will be improved. As compared with the conventional hydraulic molding machine of the same scale, the molding can be performed with a power consumption of about one-third, and the running cost can be reduced.

Since there is no link or transmission mechanism between the upper and lower punches 7 and 9 and the ball screws 6 and 10 that drive these punches 7 and 9, ball screws 6 and 10 due to stretching and backlash of the members. The driving force due to is not hindered.

EFFECT OF THE INVENTION The punch compression force is detected by detecting the actual punch compression force and fed back to the set value to control it in a closed loop. Obtainable.

Since the operation of the punch is controlled by the control device via the servomotor, complicated and cumbersome mechanical setting when setting the die and the punch (die) is not required, and quick die change is possible.

 This improves the operability of the powder molding machine.

Since the upper and lower punches are driven by the direct pressure of the ball screw, the control responsiveness is high and highly accurate control can be performed.

[Brief description of drawings]

FIG. 1 is a front view showing a partially broken view. 1 ... powder molding machine, 2 ... upper wall, 3 ... middle wall, 4 ...
… Lower wall, 5 …… Frame, 6 …… Ball screw for driving upper punch, 7 …… Upper punch, 8 …… Die, 9 ……
Lower punch, 10 …… Ball screw for driving lower punch, 1
1,16 ...... Ball nut, 12 ...... Upper punch driving servo motor, 13,14,17,19 ...... Gear, 15,20 ...... Timing belt, 18 ...... Lower punch driving servo motor, 21 ...... Die mounting part, 22 ...... Fixing member, 23 ...... Press space, 24 ......
Signal and power lines, 25 ... Servo amplifier, 26 ... Control device, 27 ... Hopper, 28 ... Hose, 29 ... Feed shoe, 30,32 ... Solenoid, 31 ... Falling device, 33 ...
... shoot, 34 ... strain gauge.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nariaki Oyama 3580, Kobaba, Oshinomura, Minamitsuru-gun, Yamanashi Prefecture FANUC CORPORATION, Basic Technology Research Institute (72) Takayuki Taira, Oshinomura, Otsunomura, Minamitsuru-gun, Yamanashi Prefecture Kobaba 3580 FANUC CORPORATION Production Technology Research Laboratory (72) Inventor Zenji Inaba 3-5 Asahigaoka, Hino City, Tokyo 1-5 FANUC CORPORATION Product Development Laboratory (72) Inventor Hideo Naito 3-5 Asahigaoka, Hino City, Tokyo 1 Fanuc Co., Ltd. Product Development Laboratory (72) Inventor Kikuo Watanabe 3-5-5 Asahigaoka, Hino City, Tokyo 1 Fanuc Co., Ltd. Product Development Laboratory (72) Masaki Muranaka 3-5 Asahigaoka, Hino City, Tokyo Address 1 Fanuc Co., Ltd. Product Development Laboratory (56) Reference JP 62-202002 (JP, A) JP 63-256296 (JP, A) JP 63-120000 (JP, A) JP 61-242794 (JP, A) Actual development Sho 62- 67695 (JP, U) US Patent 3353215 (US, A)

Claims (1)

(57) [Claims] 1. A molding unit is provided with a die and a punch, a punch driving mechanism for driving the punch by a direct pressure by a ball screw is interlocked with a servomotor, and a sensor for detecting the compression force of the punch is provided. A powder molding machine characterized by comprising control means for controlling the current compression drive of the servomotor based on the compression force between the die and the punch until the output value corresponds to the set compression force.